Fabric cutting system and method

ABSTRACT

A fabric cutting system and/or method can include a mandrel having a body and first and second legs, a chuck, the chuck configured to receive either one of the legs or body to rotatingly support the mandrel. The mandrel can be rotated and the fabric mounted on the mandrel can be cut about the leg at a location beyond the end of the other leg. One of the legs can include a leg extension removable from a leg base that when removed allows the other leg to be cut beyond the end of the leg base. The fabric can be cut with a cutting laser, which may be a multi-axis laser, and/or have low power.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/831,580, filed Mar. 15, 2013, which is a continuation-in-part of U.S.application Ser. No. 12/836,083 filed Jul. 14, 2010, now U.S. Pat. No.8,540,619, granted Sep. 24, 2013, the contents of all of which areincorporated by reference herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to a fabric cutting system and method.Embodiments of the present invention are advantageous for providingtubular fabrics having evenly cut and sealed edges.

BACKGROUND OF THE INVENTION

Tubular fabrics intended for use in medical applications often havecomplex shapes and are usually cut by hand. A conventional technique forcutting fabric for use in medical applications includes manuallyheat-cutting the fabric with a soldering iron-type tool. Manualheat-cutting often results in an uneven edge and loose fibers extendingfrom the cut line. In some processes, such heat-cutting is followed bymanually trimming the cut edge with scissors under a microscope inattempt to correct uneven areas and decrease the number of loose fibers.However, because the second, trimming step is also a manual step,unevenly cut fibers from the original heat cut and/or the scissors cutcan remain along the cut edge, creating a risk for fraying. Anotherdisadvantage of such a manual cutting process is that the second cutwith scissors represents “re-work” designed to correct imprecision inthe first cut. Thus, a second, labor-intensive cutting step increasesthe cost of the manufacturing process.

In tubular fabrics, for example, fabrics for use as an endovasculargraft, the fabric is manually rotated to cut the fabric around thecircumference of the tube. A disadvantage of manually rotating andcutting the tubular fabric is that moving the fabric from one positionto another can further cause imprecise or even cuts. In addition, manualcutting can lead to variability in quality of cuts between differentoperators.

After the fabric is cut twice—first by a soldering iron-type tool andthen by trimming with scissors—the fabric edge can be placed under amicroscope and “lightly” heat sealed so as not to further disturb thetrimmed edge. However, a disadvantage of “light” heat sealing is thatroutine handling of the fabric can disrupt the “light” seal, therebyallowing cut yarn ends to become loose and possibly cause the fabric tofray and/or unravel.

Some tubular fabrics can have two or more adjacent tubular limbs, forexample, an endovascular graft that has bifurcated limbs for placementinto two smaller arteries branching from a larger artery. Suchadjacent-limbed tubular fabrics create another cutting challenge. Atubular fabric having two adjacent limbs can be mounted on a mandrel forrotating while a cut is being made about the circumference of the limbs.However, when the tubular fabric is rotated, a cutting tool cannot reachthe “inside” portions of the limbs that are facing each other. In someconventional cutting techniques, the legs of the mandrel are loosenedfrom the mandrel body, rotated, and re-tightened so as to expose theuncut portions for cutting. This movement of the mandrel legs can causemovement of the fabric about the limbs. As a result, such movement inconventional cutting techniques can cause unevenness between the twopartial cuts on each limb, and undesirably allows one limb to be cut adifferent length than the other limb.

The tolerance for cuts of fabrics used in many medical devices isnarrow, for example, less than about 0.5 mm from the intended line ofcut. Therefore, quality control variances in manually rotated and cutfabrics and in fabrics having adjacent tubes that are partially cut,repositioned, and finish cut are often unacceptable in fabrics designedfor use in medical applications, particularly in implantable medicaldevices.

Thus, there is a need to provide a fabric cutting system and method thatprovide reliably precise cuts. There is also a need for such a fabriccutting system and method that meet quality control requirements fortubular fabrics used in medical applications. There is also a need forsuch a fabric cutting system and method that provides a completelysealed edge at a cut location. There is also a need for such a fabriccutting system and method that are efficient and cost-effective.

SUMMARY OF THE INVENTION

The present invention provides a fabric cutting system and method. In anillustrative embodiment, a fabric cutting system can comprise a mandrel,a centered chuck, an offset chuck, and a fabric cutting tool. Themandrel can be configured to support a tubular fabric having a pluralityof fabric limbs, and comprise a body, a first leg, and a second legshorter than the first leg. The centered chuck can be fixedly attachedto a work surface and configured to receive either one of the mandrellegs or the body to rotatingly support the mandrel in the center of thecentered chuck. The offset chuck can be spaced apart from and opposed tothe centered chuck, movably attached to the work surface, and configuredto receive either one of the mandrel legs or the body to rotatinglysupport the mandrel at a point offset from the center of the offsetchuck. When the first leg is inserted into the centered chuck and themandrel body is inserted into the offset chuck, the mandrel can berotated and the fabric mounted on the mandrel can be cut about the firstleg at a location beyond the end of the second leg.

In some embodiments, the first leg can further comprise a leg base and aleg extension removably attachable to the leg base. When the legextension is removed from the leg base, the second leg is inserted intothe centered chuck, and the mandrel body is inserted into the offsetchuck, the mandrel can be rotated and the fabric can be cut about thesecond leg at a location beyond the end of the first leg. In someembodiments, when the mandrel body is inserted into the centered chuckand the second leg is inserted into the offset chuck, the mandrel can berotated and the fabric can be cut about the mandrel body. In each ofthese embodiments, the fabric on the mandrel can be cut by the cuttingtool having a line of contact with the particular location unimpeded bythe other leg. In certain embodiments, the fabric cut on the mandrelcomprises a vascular graft.

In some embodiments, the fabric cutting tool can comprise a cuttinglaser. The cutting laser can have the capability to be programmed withdifferent focal distances for cutting different diameters on themandrel. In certain embodiments, the cutting laser can comprise amulti-axis laser having a plurality of power heads, each power headadapted to emit a laser beam to a different focal cutting point. Incertain embodiments, the cutting laser can emit a laser beam havingbetween about 10 and about 35 watts of power to cut the fabric.

In some embodiments, an alternative fabric cutting system can comprise amandrel, a chuck, and a fabric cutting tool. The mandrel can beconfigured to support a tubular fabric having a plurality of fabriclimbs, and comprise a body, a first leg, and a second leg shorter thanthe first leg. The chuck can be fixedly attached to a work surface andconfigured to receive either one of the mandrel legs or the body torotatingly support the mandrel in the center of the chuck. When eithermandrel leg or the mandrel body is inserted into the chuck, the mandrelcan be rotated and the fabric mounted on the mandrel can be cut aboutthe mandrel at that location.

Some embodiments of the present invention can include a method ofcutting a fabric utilizing the fabric cutting systems described herein.

Features of a fabric cutting system and method of the present inventionmay be accomplished singularly, or in combination, in one or more of theembodiments of the present invention. As will be realized by those ofskill in the art, many different embodiments of a fabric cutting systemand method according to the present invention are possible. Additionaluses, advantages, and features of the invention are set forth in theillustrative embodiments discussed in the detailed description hereinand will become more apparent to those skilled in the art uponexamination of the following.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side view of a fabric cutting system comprisinga mandrel, a centered chuck, and an offset chuck in an embodiment of thepresent invention.

FIG. 2 is a diagrammatic side view of the fabric cutting system shown inFIG. 1, in which the leg extension of one leg of the mandrel isseparated from the base of the leg in an embodiment of the presentinvention.

FIG. 3 is a diagrammatic side view of the fabric cutting system shown inFIGS. 1 and 2, in which the positions of the mandrel legs relative tothe centered chuck are reversed in an embodiment of the presentinvention.

FIG. 4 is a diagrammatic side view of the fabric cutting system shown inFIGS. 1-3, in which the positions of the mandrel body and legs arereversed relative to the centered and offset chucks in an embodiment ofthe present invention.

FIG. 5A is a diagrammatic top view of the centered chuck shown in FIG.1.

FIG. 5B is a diagrammatic side view of the centered chuck shown in FIG.1.

FIG. 5C is a diagrammatic perspective view of the centered chuck shownin FIG. 1.

FIG. 6A is a diagrammatic top view of the offset chuck shown in FIG. 1.

FIG. 6B is a diagrammatic side view of the offset chuck shown in FIG. 1.

FIG. 7 is a diagrammatic side view of a fabric cutting system comprisinga mandrel, a centered chuck, and an offset chuck in another embodimentof the present invention.

FIG. 8A is a diagrammatic top view of the centered chuck shown in FIG.7.

FIG. 8B is a diagrammatic side view of the centered chuck shown in FIG.7.

FIG. 8C is a diagrammatic perspective view of the centered chuck shownin FIG. 7.

FIG. 9A is a diagrammatic top view of the offset chuck shown in FIG. 7.

FIG. 9B is a diagrammatic side view of the offset chuck shown in FIG. 7.

FIG. 10A is a diagrammatic top view of a centered chuck in anotherembodiment of the present invention.

FIG. 10B is a diagrammatic top view of a centered chuck in anotherembodiment of the present invention.

FIG. 11 is a diagrammatic side view of a fabric cutting systemcomprising a mandrel, a centered chuck, and an offset chuck similar tothe embodiment in FIGS. 1-4 and having legs comprising the same length.

FIG. 12 is a view of a microscopic photographic view of the edge of atubular fabric manually cut with a soldering iron-type tool in aconventional cutting process.

FIG. 13 is a view of a microscopic photographic view of the edge ofanother tubular fabric manually cut with a soldering iron-type tool in aconventional cutting process.

FIG. 14 is a microscopic photographic view of the edge a long limb of atubular fabric cut with a laser in accordance with an embodiment of thepresent invention.

FIG. 15 is a microscopic photographic view of the edge a short limb of atubular fabric cut with a laser in accordance with an embodiment of thepresent invention.

FIG. 16 is a microscopic photographic view of the edge the body of atubular fabric cut with a laser in accordance with an embodiment of thepresent invention.

FIG. 17 is a diagrammatic side view of an alternative embodiment fabriccutting system.

DETAILED DESCRIPTION

For the purposes of this specification, unless otherwise indicated, allnumbers expressing quantities, conditions, and so forth used in thespecification are to be understood as being modified in all instances bythe term “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification areapproximations that can vary depending upon the desired propertiessought to be obtained by the embodiments described herein. At the veryleast, and not as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the described embodiments are approximations, thenumerical values set forth in the specific examples are reported asprecisely as possible. Any numerical value, however, inherently containscertain errors necessarily resulting from the standard deviation foundin their respective testing measurements. Moreover, all ranges disclosedherein are to be understood to encompass any and all subranges subsumedtherein. For example, a stated range of “1 to 10” should be consideredto include any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more, e.g. 1 to 6.1, and ending with amaximum value of 10 or less, for example, 5.5 to 10.

For the purposes of this specification, terms such as “forward,”“rearward,” “front,” “back,” “right,” “left,” “upwardly,” “downwardly,”and the like are words of convenience and are not to be construed aslimiting terms. As used in this specification and the appended claims,the singular forms “a,” “an,” and “the” include plural referents unlessthe context clearly dictates otherwise. Thus, for example, the term “aleg” is intended to mean a single leg or more than one leg. In addition,any reference referred to as being “incorporated herein” is to beunderstood as being incorporated in its entirety.

The present invention can include embodiments of a fabric cuttingsystem. Such a system can be utilized to provide tubular fabrics havingmore than one limb, or lumen, in which the fabric has quality-cut andwell-sealed edges that resist fraying. As shown in the illustrativeembodiment in FIGS. 1-6 and 11, the fabric cutting system 10 cancomprise two chucks 12, 14 and a mandrel 16. For purposes herein,“chuck” is defined as a device that holds a tool or the material beingworked on in a machine or to a work surface. For purposes herein,“mandrel” is defined as a rod-like structure about which material can beshaped. For example, the mandrel 16 can be a cylindrically-shaped, ortubular-shaped, metal structure about which a fabric can be shaped to aform suitable for a tubular implantable medical application, such as avascular graft.

In the embodiment shown in FIGS. 1-6, the two chucks 12, 14 include afirst, centered chuck 12 that is fixedly attached to a work surface 18,and a second, offset chuck 14 that is spaced apart from the centeredchuck 12 and movably attached to the work surface 18. The offset chuck14 can be moved on the work surface 18 along a direction of movement 20toward and away from the centered chuck 12. The offset chuck 14 can bemoved toward the centered chuck 12 and clamped with a clamping mechanism22 into a position on the work surface 18 so as to secure the mandrel 16between the two chucks 12, 14 for working on fabric on the mandrel 16.The offset chuck 14 can be moved away from the centered chuck 12 torelease the mandrel 16 from the two chucks 12, 14.

The mandrel 16 can include a body 24 and at least one limb, or leg,having a lumen and extending from the mandrel body 24. In the embodimentshown in FIGS. 1-4, the mandrel 16 can include a first, longer leg 26and a second, shorter leg 28. Such a mandrel leg configuration can beutilized for forming a fabric having a longer limb and a shorter limbuseful, for example, in a vascular graft implantable into an artery andtwo unaligned or uneven arterial branches.

The mandrel 16 can be rotatably positioned between the two spaced-apartchucks 12, 14. Each of the chucks 12, 14 can be substantially the samesize as the other, and the center of each chuck 12, 14 can be the samevertical distance from the work surface 18. In the embodiment in FIGS.1-4 and 11, each of the centered and offset chucks 12, 14, respectively,includes a tapered mount 30 extending outwardly from the respectivechuck 12, 14 toward the other chuck 12, 14. In the centered chuck 12,the tapered mount 30 extends outwardly from the center of the chuck 12,as shown in FIGS. 1-4, 5A, 5B, 5C, and 11. In the offset chuck 14, thetapered mount 30 extends outwardly from a position offset below thecenter of the chuck 14 closer to the work surface 18 than the taperedmount 30 in the centered chuck 12, as shown in FIGS. 1-4, 6A, 6B, and11. The offset of the tapered mount 30 from the center of the offsetchuck 12 allows the larger diameter body 24 and the smaller diameterlegs 26, 28 of the mandrel 16 to rotate together. The tapered mounts 30can have the same configuration (such as same size and shape) so thateach tapered mount 30 can be inserted into either of the ends of thelarger base 32 of the mandrel body 24 and/or one of the legs 26, 28 ofthe mandrel 16. The ends of the mandrel base 32 and the legs 26, 28 canbe configured to receive the tapered mounts 30, for example, in aconfiguration mated to the size and shape of the tapered mounts 30.

Each of the chucks 12, 14 can include at least two concentric grooves34, 36 formed in the face of the chucks 12, 14, as shown in theembodiment in FIGS. 1-4, and more particularly in FIGS. 5A, 5C, and 6A.Each of the grooves 34, 36 is centered about the tapered mount 30extending outwardly from the chuck 12, 14. In some embodiments, themandrel 16 can be hollow or partially hollow. Preferably, at least theends of the first and second legs 26, 28, respectively, and the base 32of the mandrel 16 are hollow so that the ends of the legs 26, 28 and themandrel base 32 can be inserted into the grooves 34, 36 in the chucks12, 14. One of the grooves is an inner, leg groove 34 encircling thebase of the tapered mount 30. The leg groove 34 is sized to allow theends of the first and second legs 26, 28, respectively, to be insertedinto the leg groove 34 about the tapered mount 30. Another groove is anouter, body groove 36 having a circumference larger than that of the leggroove 34. The body groove 36 is sized to allow the end of the base 32of the mandrel body 24 to be inserted into the body groove 36. The endsof the legs 26, 28 and the mandrel body 24 can be press fit into the leggroove 34 and body groove 36, respectively, and held in place in thechucks 12, 14 by pressure from the chucks 12, 14 on the mandrel 16 whenthe offset chuck 14 is clamped into position on the work surface 18. Inthis manner, when the mandrel 16 is positioned between the chucks 12,14, the mandrel 16 is supported within the leg and body grooves 34, 36,respectively, for rotation with and/or by the chucks 12, 14.

In some embodiments, the centered and offset chucks 12, 14,respectively, can each include more than one leg groove 34. For example,each chuck 12, 14 can include two leg grooves 34, each having adifferent circumference so as to accommodate mandrel legs havingdifferent diameters.

In another embodiment, as shown in FIG. 7, each of the centered andoffset chucks 12, 14, respectively, includes a stepped mount having afirst stepped portion 31, a second stepped portion 33, and a thirdstepped portion 35. The first portion 31 has a diameter that fits withinthe circumference, and extends outwardly from the center of, the bodygroove 36 in the respective chuck 12, 14 toward the other chuck 12, 14.The second portion 33 has a diameter smaller than the diameter of thefirst stepped portion 31, and extends outwardly from the center of thefirst portion 31. The third stepped portion 35 has a diameter smallerthan the diameter of the second stepped portion 33, and extendsoutwardly from the center of the second portion 33. A pair of roundedleg pins 37 extends outwardly from the second stepped portion 33adjacent the third stepped portion 35. The leg pins 37 can be onopposite sides of the third stepped portion 35. The leg pins 37 can beany suitable material, such as the material comprising the chuck 12, 14,for example, a polymeric material, or a metallic material such asstainless steel.

In the centered chuck 12, the stepped mount portions 31, 33, 35 extendoutwardly from the center of the chuck 12, as shown in FIGS. 7, 8A, 8B,and 8C. In the offset chuck 14, the stepped mount portions 31, 33, 35extend outwardly from a position offset below the center of the chuck 14closer to the work surface 18 than the stepped mount portions 31, 33, 35in the centered chuck 12, as shown in FIGS. 7, 9A, and 9B. The offset ofthe stepped mount portions 31, 33, 35 from the center of the offsetchuck 12 allows the larger body 24 and the smaller legs 26, 28 of themandrel 16 to rotate together. The stepped mount portions 31, 33, 35 caneach have the same configuration (such as same size and shape) so thateach stepped mount can be inserted into the end of either of the legs26, 28 of the mandrel 16 or the mandrel body 24. The ends of the legs26, 28 can be configured to engagingly fit about the third steppedportion 35 and leg pins 37, for example, in a configuration mated to thesize and shape of the third stepped portion 35 and leg pins 37. Forexample, as shown in FIG. 7, the ends of the legs 26, 28 can eachinclude a pair of opposed notches 29. The notches 29 can be configuredso as to slide over and engage the leg pins 37 about the stepped mountthird portion 35. When the notches 29 in one of the mandrel legs 26, 28engage the leg pins 37, the mandrel 16 can be rotated with the chuck 12,14.

As shown in the embodiment in FIGS. 7, 8A, 8C, and 9A, each of thechucks 12, 14 includes the body groove 36 formed in the face of thechucks 12, 14. The body groove 36 is centered about the stepped mountportions 31, 33, 35. At least the end of the mandrel base 32 is hollowso that the end of the mandrel base 32 can be inserted over the steppedmount portions 31, 33, 35 and into the body groove 36 in the chucks 12,14. The end the mandrel body 24 can be press fit into the body groove 36and held in place in the chucks 12, 14 by pressure from the chucks 12,14 on the mandrel 16 when the offset chuck 14 is clamped into positionon the work surface 18. In this manner, when the mandrel 16 ispositioned between the chucks 12, 14, one of the mandrel legs 26, 28 issupported by the stepped mount portions 31, 33, 35 extending from one ofthe chucks 12, 14 and the mandrel body 24 is supported by the bodygroove 36 in the other chuck 12, 14 for rotation with and/or by thechucks 12, 14.

As shown in FIGS. 8A, 8C, and 9A, at least one base pin 39 can extendbetween the inner and outer diameters of the body groove 36 in thechucks 12, 14. The base pin 39 can be any suitable material, such as thematerial comprising the chuck 12, 14, for example, a polymeric material,or a metallic material such as stainless steel. As shown in FIG. 7, theend of the mandrel base 32 can include a pair of opposed notches 29. Thenotches 29 can be configured so that one of the notches 29 can to slideover and engage the base pin 39 in the body groove 36. When one of thenotches 29 in the mandrel base 32 engages the base pin 39, the mandrel16 can be rotated with the chuck 12, 14. In some embodiments, the chucks12, 14 shown in FIG. 1-6 can also include at least one base pin 39extending between the inner and outer diameters of the body groove 36for engaging the notch 29 in the mandrel base 32.

In another embodiment, as shown in FIGS. 10A and 10B, an alternativecentered chuck 13 can include a universal leg engaging member 72 havinga “Y” shape. The universal leg engaging member 72 can extend outwardlyfrom the chuck, for example, about ⅛ inch to about ¼ inch. The universalleg engaging member 72 can comprise various materials, such as thematerial comprising the chuck 12, 14, for example, a polymeric material,or a metallic material such as stainless steel. The universal legengaging member 72 can be secured to the face of the chuck 13 in variousways. In a preferred embodiment, the chuck 13 includes a Y-shaped groove(not shown) in the face of the chuck corresponding to the shape anddimensions of the leg engaging member 72. A stainless steel leg engagingmember 72 is inserted into and fixedly attached to the groove such thatthe leg engaging member 72 is secured to and extends upwardly from thechuck 13.

The ends of the mandrel legs 26, 28 can be configured to engagingly fitonto the universal leg engaging member 72. For example, the ends of thelegs 26, 28 can each include three notches 29 equally spaced about thecircumference of the ends of the legs 26, 28 (that is, spaced 120degrees apart). The notches 29 can be configured so as to slide over andengage the universal leg engaging member 72. When the notches 29 in oneof the mandrel legs 26, 28 engages the universal leg engaging member 72,the mandrel 16 can be rotated with the chucks 13, 14.

Each of the arms 76 of the Y-shaped universal leg engaging member 72extend outwardly from the center of the chuck 13 toward the edge of theface of the chuck 13. In this configuration, a mandrel leg 26, 28 havinga first, smaller diameter can fit about the leg engaging member 72 at apoint relatively close to the center of the chuck 13, while a mandrelleg 26, 28 having a second, larger diameter can fit about the legengaging member 72 farther from the center of the chuck 13 than thesmaller diameter leg 26, 28. Thus, mandrel legs 26, 28 having differentdiameters can fit about the leg engaging member 72. In this way, someembodiments of the fabric cutting system 10 including the chuck 13 canaccommodate mandrel legs 26, 28 having different diameters withouthaving to change the chuck 13.

In some embodiments the centered chuck 13 can include the body groove36, as shown in FIG. 10A. The centered chuck 13 having the universal legengaging member 72 does not include the leg groove 34. In thisembodiment, the universal leg engaging member 72 can extend in a “Y”shape from the center of the chuck 13 toward, and/or the entire distanceto, the inside diameter of the body groove 36. In other embodiments, thecentered chuck 13 does not include the body groove 36, as shown in FIG.10B. In such an embodiment, the universal leg engaging member 72 canextend in a “Y” shape from the center of the chuck 13 toward, and/or theentire distance to, the outer circumferential perimeter of the chuck 13.Accordingly, the centered chuck 13 having the universal leg engagingmember 72 can accommodate mandrel legs 26, 28 having a diameterequivalent to the diameter 74 of a circle circumscribing the universalleg engaging member 72.

The centered chuck 13 having the universal leg engaging member 72 can beutilized in conjunction with the offset chuck 14 having the body groove36, as shown in FIGS. 1-6 and 11, to support a mandrel between thechucks 13, 14 for rotation. Alternatively, the offset chuck 14 can alsoinclude the universal leg engaging member 72 extending outwardly from aposition offset from the center of the chuck 14. Thus, when utilizedwith the centered chuck 13 having the body groove 36, as shown in FIG.10A, an appropriately configured mandrel can be supported on either endby either the centered chuck 13 or the offset chuck 14 having theuniversal leg engaging member 72.

In an embodiment comprising at least the chuck 13 having the body groove36, at least the end of the mandrel base 32 is hollow so that the end ofthe mandrel base 32 can be inserted over the universal leg engagingmember 72 and into the body groove 36 in the chuck 13. The end themandrel body 24 can be press fit into the body groove 36 and held inplace in the chucks 13, 14 by pressure from the chucks 13, 14 on themandrel 16 when the offset chuck 14 is clamped into position on the worksurface 18. In this manner, when the mandrel 16 is positioned betweenthe chucks 13, 14, one of the mandrel legs 26, 28 is supported by theuniversal leg engaging member 72 extending from one of the chucks 13, 14and the mandrel body 24 is supported by the body groove 36 in the otherchuck 13, 14 for rotation with and/or by the chucks 13, 14.

After a fabric is mounted onto the mandrel 16 and the mandrel 16 ispositioned between the centered and offset chucks 12, 14, respectively,the fabric can be cut at desired locations. The fabric can be any fabricsuitable for cutting on a mandrel. In certain embodiments, the fabriccan be fabric suitable for forming implantable tubular medical devices.For example, in particular applications, the fabric can comprisepolypropylene and/or polyester.

In operation, the first, longer leg 26 of the mandrel 16 is aligned andengaged with the centered chuck 12 along a first longitudinal axis 38through the center of the centered chuck 12 and the center 40 of thefirst leg 26. In some embodiments, as in FIGS. 1-6 and 11, the end ofthe first leg 26 is inserted into the leg groove 34 in the centeredchuck 12. In other embodiments, as in FIGS. 7-9, the notches 29 in theend of the first leg 26 are slid over and engage the leg pins 37 aboutthe stepped mount third portion 35. In still other embodiments, as inFIG. 10, the notches 29 in the ends of the first leg 26 are mounted ontoand engage the universal leg engaging member 72. The base 32 of themandrel 16 is aligned and engaged with the offset chuck 14 along asecond longitudinal axis 42 through the center of the offset chuck andthe center 44 of the base 32 of the mandrel body 24. The end of themandrel base 32 is inserted into the body groove 36 in the offset chuck14. The offset chuck 14 is then moved toward the centered chuck 12 suchthat the mandrel 16 is supported on each end by one of the chucks 12, 14for rotation. Once the fabric cutting system 10 assemblies is in placefor rotating the mandrel 16, the offset chuck 14 is clamped to the worksurface 18 with the clamping mechanism 22 to secure the assembly inplace for operation.

Then, a fabric mounted onto the mandrel 16 can be cut about the firstleg 26. The first leg cut 46 can be located on the first leg 26 beyondthe end of the second leg 28 toward the centered chuck 12. The mandrel16 can be rotated about the first and second longitudinal axes 38, 42,respectively, in order to complete the cut 46 about the entirecircumference of the first leg 26. In this way, the fabric cuttingsystem 10 provides a direct and unimpeded line of contact between afabric cutting tool 48 and the first leg 26. That is, the first leg cut46 can be made while rotating the mandrel 16 without interference fromthe second leg 28 between the fabric cutting tool 48 and the first leg26.

To make a cut in fabric on the second, shorter leg 28, the mandrel 16 isfirst removed from the chucks 12, 14. The clamping mechanism 22 securingthe offset chuck 14 to the work surface 18 can be released, and theoffset chuck 14 moved away from the centered chuck 12 along thedirection of movement 20 on the work surface 18. When the two chucks 12,14 are thusly separated, the mandrel 16 can be removed from the chucks12, 14.

In some embodiments, the first, longer leg 26 can comprise a leg base 50and a leg extension 52 separable from the leg base 50, as shown in FIG.2. In other embodiments, each of the legs 26, 28 on the mandrel 16 caninclude a leg base 50 and a separable leg extension 52 such that legextensions 52 of various lengths can be utilized with either of the legbases 50.

The leg extension 52 can be removably attached to the leg base 50 invarious ways. Preferably, the leg extension 52 can be attached to andremoved from the leg base 50 with a quick release mechanism. In oneillustrative embodiment of such a quick release mechanism, the legextension 52 can have a hollow bore sufficiently large to receive athreaded screw 54 through the bore. The leg base 50 can include screwreceiving threads 56 inside the leg base 50. When the leg extension 52and the leg base 50 are abutted together end-to-end, the screw 54 can beinserted through the leg extension bore and threaded into the screwreceiving threads 56 in the leg base 50 to secure the leg extension 52to the leg base 50. For example, the screw 54 can have a hexagonalsocket in the head of the screw 54, and a hex key, or Allen wrench, canbe inserted through the bore of the leg extension 52 to tighten thescrew 54 into the leg base 50 and loosen the screw 54 from the leg base50. In this way, the leg extension 52 can be quickly and easily securedto and removed from the leg base 50.

In other embodiments, the quick release mechanism can comprise othermeans of securing the leg extension 52 to the leg base 50. As oneexample, one of the ends of the leg extension 52 or the leg base 50 canhave a “male” configuration insertable into a “female” configuration atthe end of the other of the leg extension 52 or leg base 50. When theends of the leg extension 52 and leg base 50 are joined together,pressure from the two chucks 12, 14 on the mandrel 16 can hold the legextension 52 and leg base 50 together during operation of the fabriccutting system 10. When the mandrel 16 is removed from the chucks 12,14, the leg extension 52 can be manually removed from the leg base 50.

After the leg extension 52 is removed from the leg base 50 of the firstleg 26, as shown in FIG. 2, the portion of the fabric limb (not shown)extending beyond the leg base 50 can be turned back onto itself to movethat fabric limb out of the way for cutting the fabric on the second leg28. Optionally, an O-ring may be placed about the folded back fabriclimb to secure the folded portion about the leg base 50.

Once the mandrel 16 is removed from the chucks 12, 14 and the legextension 52 removed from the leg base 50, the second leg 28 (which isnow the longer of the two legs 26, 28) can be aligned and engaged withthe centered chuck 12 along the first longitudinal axis 38 through thecenter of the centered chuck 12 and the center 60 of the second leg 28.In some embodiments, as in FIGS. 1-6, the end of the second leg 28 isinserted into the leg groove 34 in the centered chuck 12. In otherembodiments, as in FIGS. 7-9, the notches 29 in the end of the secondleg 28 are slid over and engage the leg pins 37 about the stepped mountthird portion 35. In still other embodiments, as in FIG. 10, the notches29 in the ends of the second leg 28 are mounted onto and engage theuniversal leg engaging member 72.

As the second leg 28 is aligned and engaged with the centered chuck 12,the base 32 of the mandrel 16 is aligned and engaged with the offsetchuck 14 along the second longitudinal axis 42 through the center of theoffset chuck 14 and the center 44 of the base 32 of the mandrel body 24.The end of the mandrel base 32 is inserted into the body groove 36 inthe offset chuck 14. The offset chuck 14 is then moved toward thecentered chuck 12 such that the mandrel 16 is supported on each end byone of the chucks 12, 14 for rotation. When the fabric cutting system 10assembly is in place for rotating the mandrel 16, the offset chuck 14 isclamped to the work surface 18 with the clamping mechanism 22 to securethe assembly in place for operation. If the second leg 28 has adifferent diameter than the first leg 26, the fabric cutting tool 48 canbe adjusted to accommodate for the difference in diameter.

Then, the fabric mounted onto the mandrel 16 can be cut about the secondleg 28. The second leg cut 58 can be located on the second leg 28 beyondthe end of the leg base 50 of the first leg 26 toward the centered chuck12. The mandrel 16 can be rotated about the first and secondlongitudinal axes 38, 42, respectively, in order to complete the cut 58about the entire circumference of the second leg 28. In this way, thefabric cutting system 10 provides a direct and unimpeded line of contactbetween the fabric cutting tool 48 and the second leg 28. That is, thesecond leg cut 58 can be made while rotating the mandrel 16 withoutinterference from the first leg 26 between the fabric cutting tool 48and the second leg 28.

To make a cut in fabric on the body 24 of the mandrel 16, the mandrel 16is again removed from the chucks 12, 14. The mandrel 16 can be removedfrom the chucks 12, 14 by releasing the clamping mechanism 22 securingthe offset chuck 14 to the work surface 18, and moving the offset chuck14 away from the centered chuck 12 along the direction of movement 20 onthe work surface 18. In some embodiments of the fabric cutting system10, once the mandrel 16 is removed from the chucks 12, 14, it can bereversed in position relative to the two chucks 12, 14, and the body 24of the mandrel 16 aligned and engaged with the centered chuck 12 alongthe first longitudinal axis 38 through the center of the centered chuck12 and the center 44 of the mandrel base 32. This alignment is shown inFIG. 4. The end of the mandrel base 32 is inserted into the body groove36 in the centered chuck 12.

The second leg 28 (now the longer of the two legs 26, 28) is aligned andengaged with the offset chuck 14 along the second longitudinal axis 42through the center of the offset chuck 14 and the center 60 of thesecond leg 28. In some embodiments, as in FIGS. 1-6, the end of thesecond leg 28 is inserted into the leg groove 34 in the offset chuck 14.In other embodiments, as in FIGS. 7-9, the notches 29 in the end of thesecond leg 28 are slid over and engage the leg pins 37 about the steppedmount third portion 35 in the offset chuck 14. In still otherembodiments, the notches 29 in the ends of the second leg 28 are mountedonto an offset chuck having the universal leg engaging member 72 as inFIG. 10, but offset from the center of the chuck.

The offset chuck 14 is then moved toward the centered chuck 12 such thatthe mandrel 16 is supported on each end by one of the chucks 12, 14 forrotation. When the fabric cutting system 10 assembly is in place forrotating the mandrel 16, the offset chuck 14 is clamped to the worksurface 18 with the clamping mechanism 22 to secure the assembly inplace for operation.

Then, the fabric mounted onto the mandrel 16 can be cut about themandrel body 24. The body cut 62 can be located at a predeterminedlocation on the mandrel body 24. The fabric cutting tool 48 can beadjusted to accommodate for the larger diameter of the mandrel body 24as compared to the diameter of the first and/or second legs 26, 28,respectively. The mandrel 16 can be rotated about the first and secondlongitudinal axes 38, 42, respectively, in order to complete the cut 62about the entire circumference of the mandrel body 24.

In some embodiments of the fabric cutting system 10, whichever portionof the mandrel 16 on which fabric is being cut may be placed on thecentered chuck 12 so that the fabric cutting tool 48 can be pre-alignedwith that portion of the mandrel 16, and moving the cutting tool 48 canbe avoided. In this way, the cutting tool 48 does not have to be reseteach time the mandrel 16 is repositioned. The cutting tool 48 can bepreset to cut to a location along the first longitudinal axis 38 betweenthe center of the centered chuck 12 and the center of the portion of themandrel 16 on which the fabric is being cut. The distance from the firstlongitudinal axis 38 to which the cutting tool 48 is set to cut can varydepending on the diameter of the portion of the mandrel 16 on whichfabric is being cut.

Some embodiments of the fabric cutting system 10 can be utilized to cutfabric about the mandrel 16 comprising legs having substantially thesame initial length, as shown in the embodiment in FIG. 11. In such anembodiment, each of the legs 26, 28 can include a leg base 50 and aseparable leg extension 52. Such an embodiment can be utilized forforming a fabric having a longer limb and a shorter limb.

In the embodiment in FIG. 11, the leg extension 52 can be removed fromthe leg base 50 on the second leg 28, as shown in FIG. 2. The portion ofthe fabric limb (not shown) extending beyond the leg base 50 can beturned back onto itself to move that fabric limb out of the way forcutting the fabric on the first leg 26.

The first leg 26 of the mandrel 16 is aligned and engaged with thecentered chuck 12 along a first longitudinal axis 38 through the centerof the centered chuck 12 and the center 40 of the first leg 26. In someembodiments, as in FIGS. 1-6 and 11, the end of the first leg 26 isinserted into the leg groove 34 in the centered chuck 12. In otherembodiments in which the mandrel 16 comprises legs 26, 28 havingapproximately the same initial length, each leg 26, 28 can comprise thenotches 29 in the ends of the legs 26, 28, as in FIGS. 7-9. The notches29 in the end of the first leg 26 can be slid over and engage the legpins 37 about the stepped mount third portion 35. In still otherembodiments in which the mandrel 16 comprises legs 26, 28 havingapproximately the same initial length, the notches 29 in the end of thefirst leg 26 can be mounted onto and engage the universal leg engagingmember 72, as in FIGS. 10A and 10B. The base 32 of the mandrel 16 isaligned and engaged with the offset chuck 14 along a second longitudinalaxis 42 through the center of the offset chuck and the center 44 of thebase 32 of the mandrel body 24. The end of the mandrel base 32 isinserted into the body groove 36 in the offset chuck 14. In otherembodiments, the end of the mandrel base 32 can include a pair ofopposed notches 29, as shown in FIG. 7, such that one of the notches 29slides over and engages the base pin 39 in the body groove 36. When themandrel base 32 is inserted into the body groove 36 and/or one of thenotches 29 in the mandrel base 32 engages the base pin 39, the mandrel16 can be rotated with the chuck 12, 14. The offset chuck 14 is thenmoved toward the centered chuck 12 such that the mandrel 16 is supportedon each end by one of the chucks 12, 14 for rotation. The offset chuck14 is then clamped to the work surface 18 with the clamping mechanism 22to secure the assembly in place for operation.

Then, a fabric mounted onto the mandrel 16 can be cut about the firstleg 26. The first leg cut 46 can be located on the first leg 26 beyondthe end of the leg base 50 of the second leg 28 toward the centeredchuck 12. The mandrel 16 can be rotated about the first and secondlongitudinal axes 38, 42, respectively, in order to complete the cut 46about the entire circumference of the first leg 26 without interferencefrom the second leg 28 between the fabric cutting tool 48 and the firstleg 26.

To make a cut in fabric on the second leg 28, the mandrel 16 is firstremoved from the chucks 12, 14. The clamping mechanism 22 securing theoffset chuck 14 to the work surface 18 can be released, and the offsetchuck 14 moved away from the centered chuck 12 along the direction ofmovement 20 on the work surface 18. When the two chucks 12, 14 arethusly separated, the mandrel 16 can be removed from the chucks 12, 14.

The leg extension 52 can then be reconnected to the leg base 50 on thesecond leg 28, and the fabric folded onto itself on the leg base 50 ofthe second leg 28 can be extended back onto the leg extension 52. Next,the leg extension 52 can be removed from the leg base 50 of the firstleg 26, as shown in FIG. 2, and the portion of the fabric limb (notshown) extending beyond the leg base 50 can be turned back onto itselfto move that fabric limb out of the way for cutting the fabric on thesecond leg 28.

Once the mandrel 16 is removed from the chucks 12, 14 and the legextension 52 is removed from the leg base 50 of the first leg 26, thesecond leg 28 (which is now the longer of the two legs 26, 28) can bealigned and engaged with the centered chuck 12 along the firstlongitudinal axis 38 through the center of the centered chuck 12 and thecenter 60 of the second leg 28. The end of the second leg 28 can beinserted into the leg groove 34 in the centered chuck 12, as in theembodiment in FIGS. 1-6. In other embodiments in which each leg 26, 28comprises the notches 29 in the ends of the legs 26, 28 (as in FIGS.7-9), the notches 29 in the end of the second leg 28 can be slid overand engage the leg pins 37 about the stepped mount third portion 35. Instill other embodiments, the notches 29 in the end of the second leg 28can be mounted onto and engage the universal leg engaging member 72, asin FIGS. 10A and 10B.

As the second leg 28 is aligned and engaged with the centered chuck 12,the base 32 of the mandrel 16 is aligned and engaged with the offsetchuck 14 along the second longitudinal axis 42 through the center of theoffset chuck 14 and the center 44 of the base 32 of the mandrel body 24.The end of the mandrel base 32 is inserted into the body groove 36 inthe offset chuck 14. In other embodiments in which the end of themandrel base 32 includes a pair of opposed notches 29 (as shown in FIG.7), one of the notches 29 can be slid over and engage the base pin 39 inthe body groove 36. When the mandrel base 32 is inserted into the bodygroove 36 and/or one of the notches 29 in the mandrel base 32 engagesthe base pin 39, the mandrel 16 can be rotated with the chuck 12, 14.The offset chuck 14 is then moved toward the centered chuck 12 such thatthe mandrel 16 is supported on each end by one of the chucks 12, 14 forrotation. The offset chuck 14 is then clamped to the work surface 18with the clamping mechanism 22 to secure the assembly in place foroperation.

Then, the fabric mounted onto the mandrel 16 can be cut about the secondleg 28. The second leg cut 58 can be located on the second leg 28 beyondthe end of the leg base 50 of the first leg 26 toward the centered chuck12. The mandrel 16 can be rotated about the first and secondlongitudinal axes 38, 42, respectively, in order to complete the cut 58about the entire circumference of the second leg 28 without interferencefrom the first leg 26 between the fabric cutting tool 48 and the secondleg 28.

To make a cut in fabric on the body 24 of the mandrel 16, the mandrel 16is again removed from the chucks 12, 14. In some embodiments of thefabric cutting system 10, once the mandrel 16 is removed from the chucks12, 14, it can be reversed in position relative to the two chucks 12,14, and the body 24 of the mandrel 16 aligned and engaged with thecentered chuck 12 along the first longitudinal axis 38 through thecenter of the centered chuck 12 and the center 44 of the mandrel base32. This alignment is shown in FIG. 4. The end of the mandrel base 32can be inserted into the body groove 36 in the centered chuck 12. Inother embodiments in which the end of the mandrel base 32 includes apair of opposed notches 29 (as shown in FIG. 7), one of the notches 29can be slid over and engage the base pin 39 in the body groove 36.

The second leg 28 (now the longer of the two legs 26, 28) is aligned andengaged with the offset chuck 14 along the second longitudinal axis 42through the center of the offset chuck 14 and the center 60 of thesecond leg 28. In some embodiments, as in FIGS. 1-6, the end of thesecond leg 28 is inserted into the leg groove 34 in the offset chuck 14.In other embodiments, as in FIGS. 7-9, the notches 29 in the end of thesecond leg 28 are slid over and engage the leg pins 37 about the steppedmount third portion 35 in the offset chuck 14. In still otherembodiments, the notches 29 in the ends of the second leg 28 are mountedonto an offset chuck having the universal leg engaging member 72 as inFIG. 10, but offset from the center of the chuck.

The offset chuck 14 is then moved toward the centered chuck 12 such thatthe mandrel 16 is supported on each end by one of the chucks 12, 14 forrotation, and the offset chuck 14 is clamped to the work surface 18 withthe clamping mechanism 22 to secure the assembly in place for operation.The mandrel 16 can then be rotated about the first and secondlongitudinal axes 38, 42, respectively, in order to complete the cut 62of the fabric about the entire circumference of the mandrel body 24.

As shown in FIGS. 1-11, in some embodiments of the fabric cutting system10, each of the chucks 12, 13, 14 can have the same size andconfiguration. That is, each of the centered chucks 12, 13 and offsetchucks 14 can have the same size and configuration of tapered mount 30,stepped mount portions 31, 33, 35, or universal leg engaging member 72,leg groove 34, and body groove 36 such that both the legs 26, 28 of themandrel 16 and the body 24 of the mandrel 16 can fit into and besupported by either chuck 12 or 13 and 14 for rotation. This consistencybetween chucks 12 or 13 and 14 allows interchangeability of the ends ofthe mandrel 16 with either chuck 12 or 13 and 14 so that the mandrel 16can be repositioned without having to adjust the location of the fabriccutting tool 48 between the chucks 12 or 13 and 14.

In some embodiments of the fabric cutting system 10, the mandrel 16,which is a cutting mandrel, can also be used for heat-setting fabric onthe mandrel 16. Using the mandrel 16 for both cutting and heat-settingavoids having to remove the fabric from one mandrel 16 and place it onanother mandrel. This avoids the risk of the fabric wrinkling and thepossible difficulty of placing the fabric in the proper position on theheat-setting mandrel.

In another aspect of the fabric cutting system 10, the fabric cuttingtool 48, or device, can comprise a cutting laser. Preferably, thecutting laser is programmable so that focal distances between the laserlens and the mandrel 16 can be easily and/or automatically adjusted topreset distances for quality cutting of different diameters on themandrel 16. For example, fabric mounted on a plurality of mandrel legs26, 28 can be cut adjacent the centered chuck 12, 13 by the cuttinglaser having a cutting focal distance preset for the diameter of thelegs 26, 28. When the mandrel 16 is reversed in position between the twochucks 12 or 13 and 14, fabric mounted on the mandrel body 24 can be cutadjacent the centered chuck 12 by the cutting laser having a differentcutting focal distance preset for the diameter of the mandrel body 24.Having an optimal cutting focal distance from the laser to the fabricavoids insufficient cutting when the laser is too far from the fabricand burning the fabric when the laser is too close to the fabric.

In some embodiments, the cutting laser can be a multi-axis laser. Amulti-axis laser comprises multiple power heads from which differentlaser beams can be emitted. A cutting laser beam emitted from each powerhead can be focused to a different focal point. Accordingly, fabric onthe mandrel legs 26, 28 can be cut by a first power head having a presetfocal point, or distance, for the mandrel legs 26, 28, and fabric on thelarger diameter mandrel body 24 can be cut by a second power head havinga preset focal point, or distance, for the mandrel body 24. In someembodiments of the fabric cutting system 10, fabric on the largerdiameter mandrel body 24 can be cut by a second power head of amulti-axis laser after the mandrel body 24 is removed from the offsetchuck 14 and placed onto the centered chuck 12 or 13. This allowselimination of the step of adjusting a single focus laser to a desiredcutting focal point for the larger diameter mandrel body 24. In otherembodiments, the fabric on the larger diameter mandrel body 24 can becut by a second power head of a multi-axis laser while the mandrel body24 is still secured in the offset chuck 14. This allows elimination ofthe step of removing the mandrel 16 from the chucks 12 or 13 and 14 andplacing the mandrel body 24 in the centered chuck 12.

In some embodiments, the cutting laser can utilize between about 10 andabout 35 watts of power to accomplish a cut of fabric. Lasers havingpower output in this range are sometimes referred to as “engraving”lasers. Often, cutting lasers utilize greater than 50 watts of power toaccomplish a cut. However, an engraving-type laser utilizing betweenabout 10 and about 35 watts to cut a fabric can provide cuts having astraighter edge and a better seal of the fabric edge than fabrics cutwith lasers utilizing greater than 50 watts. The quality of laser cutsfor fabric useful in medical applications can be enhanced by optimizingthe combination of power, speed, and density (wattage per square unit)of the laser. The optimal combination of these variables can varydepending on the type of fabric or material being cut.

Some embodiments of the present invention can include a method ofcutting a fabric utilizing embodiments of the fabric cutting system 10described herein. For example, one illustrative method of cutting fabriccan comprise mounting a tubular fabric having a plurality of fabriclimbs onto the mandrel 16 comprising the body 24, the first leg 26, andthe second leg 28 shorter than the first leg 26. The first leg 26 isinserted into the center of the centered chuck 12 or 13, and the mandrelbody 24 is inserted into the offset chuck 14 at a point offset from thecenter of the offset chuck 14. The mandrel 16 can then be rotatedbetween the chucks 12 or 13 and 14, and the entire circumference of thefabric about the first leg 26 can be cut at a location beyond the end ofthe second leg 28. In this way, the first leg cut 46 can be accomplishedby the fabric cutting tool 48 having a line of contact with the firstleg cut 46 location unimpeded by the second leg 28.

In some embodiments, the first leg 26 can comprise the leg extension 52removably attached to the leg base 50, and the method can furthercomprise removing the mandrel 16 from the centered chuck 12 or 13 andthe offset chuck 14, removing the leg extension 52 from the leg base 50,and folding a portion of the fabric leg extending beyond the leg base 50back onto itself on the leg base 50. The second leg 28 is inserted intothe center of the centered chuck 12 or 13, and the mandrel body 24 isinserted into the offset chuck 14 at the point offset from the center ofthe offset chuck 14. The mandrel 16 can then be rotated between thechucks 12 or 13 and 14, and the entire circumference of the fabric aboutthe second leg cut 58 at a location beyond the end of the leg base 50 ofthe first leg 28. That is, the second leg cut 58 can be accomplished bythe fabric cutting tool 48 having a line of contact with the second legcut 58 location unimpeded by the first leg 26.

In some embodiments, such a method can further comprise removing themandrel 16 from the centered chuck 12 or 13 and the offset chuck 14,inserting the mandrel body 24 into the center of the centered chuck 12or 13, and inserting the second leg 28 into the offset chuck 14 at thepoint offset from the center of the offset chuck 14. The mandrel 16 canthen be rotated between the chucks 12, 13, 14, and the entirecircumference of the fabric cut about the mandrel body 24. Preferably,the fabric about the first leg 26 and the second leg 28 is cut beforecutting the fabric about the mandrel body 24. In this way, the fulllength of the fabric on the mandrel body 24 is in place to help grip themandrel body 24 and stabilize the fabric while being cut on the legs,26, 28 resulting in more accurate first and second leg cuts, 46, 58,respectively. In certain embodiments, the cut fabric comprises avascular graft.

In some embodiments of such a method, the centered chuck 12, 13 can befixedly attached to the work surface 18 and configured to receive eitherone of the mandrel legs 26, 28 or body 24 to rotatingly support themandrel 16 in the center of the centered chuck 12. And, the offset chuck14 can be spaced apart from and opposed to the centered chuck 12, 13,movably attached to the work surface 18, and configured to receiveeither one of the mandrel legs 26, 28 or body 24 to rotatingly supportthe mandrel 16 at the point offset from the center of the offset chuck14. In certain embodiments, the method can further comprise heat-settingthe fabric on the mandrel 16.

In some embodiments of such a method, the fabric can be cut utilizing acutting laser. The cutting laser may be programmable with differentfocal distances for cutting different diameters on the mandrel. Incertain embodiments, the cutting laser can be a multi-axis laser adaptedto emit laser beams to different focal cutting points. In otherembodiments, the laser can be capable of emitting a laser beam havingbetween about 10 and about 35 watts of power to cut the fabric.

In some embodiments of such a method, the fabric cutting system 10 cancomprise the mandrel 16 comprising legs having substantially the sameinitial length, as shown in and described relative to the embodiment inFIG. 11.

A further alternative embodiment 100 of the fabric cutting system andmethod can be altered so that only a single chuck is used to support androtate the mandrel. As shown in FIG. 17, the system 100 would include asingle chuck 102. This could operate in either a horizontal or verticalalignment. In FIG. 17, the system 100 is oriented vertically. The chuck102 is fixed to the work surface 104 and structured and functionssimilar to that previously described. The mandrel 106 is similarly sizedand shape as that previously described with a body 110 and a longer leg112 and a shorter leg 114. The longer leg 112 is longer because of aremovable leg extension 113 fixed to the leg. The chuck 102 has a recess108 sized to receive either the body 110 or either of the legs 112, 114of the mandrel. Each leg 112, 114 and the body 110 has a taperedthreaded pin 116 fixed thereto. The pin 116 is designed to be receivedinto the recess 108 of the chuck 102 having a female tapped section 119therein designed to receive the threaded pin. The pin 116 is located atthe radial center of each leg 112, 114 and body 110 and provides a pointalong the vertical axis. It should be appreciated that alternativealignment devices may be used instead of a tapered pin. Such devices mayinclude a Y shaped member as described above having an attachmentmechanism, a electric magnet, any male/female temporary connections thatenable the chuck to receive the mandrel and temporarily secure it sothat it can effectively rotate the mandrel. Alignment devices such asthese are known to those skilled in the art and are mentioned asexamples and are not intended to in any way limit the scope of theembodiments described herein.

A frame 118 is fixed to the work surface 104 and extends vertically andparallel to the chuck 102 and mandrel 106 assembly. The frame 118provides support to a fabric cutting implement 120 that is slidablyattached to the frame. The fabric cutting implement 120 is preferably alaser. The height of the laser 120 may be adjusted by loosening theconnection between the laser 120 and the frame 118 and then tighteningthe connection once the desired height is achieved.

A fabric tube 122 is fitted onto the mandrel as described above. Thetube 122 has a tube body 124, a first limb 126 and a second limb 128.The first limb 126 is longer than the second limb 128. The first limb126 is received onto the first leg 112 of the mandrel 106. The secondlimb 128 is received onto the second leg 114 of the mandrel 106. Thetube body 124 is received onto the mandrel body 110.

In use, the chuck 102 receives the body 110 of the mandrel 106 byreceiving the pin 116 fixed to the end of the body. The pin 116 isreceived into the recess 108 of the chuck and held securely therein bythe threads. The pin 116 aids in enabling the mandrel to be supported bythe chuck in a vertically aligned fashion. Once the mandrel 106 issecured within the chuck 102, the chuck rotates the mandrel 106 aboutthe vertical axis of the first leg 112. As the mandrel rotates, thelaser 120 cuts the fabric first limb 126 at the first leg 112.

To cut the second fabric limb 128, the fabric first limb 126 is rolledback to expose the connection between the leg extension 113 and themandrel 106. The leg extension 113 is removed from the first leg 112 andfixedly attached to the second leg 114 of the mandrel 106. Theattachment mechanism may be threaded any other mechanism known to thoseskilled in the art. Once the leg extension 113 is fixedly attached tothe second leg 114, the first fabric limb 126 is folded back so as notto be in the way of the laser 120. When power is supplied to the chuck102, the chuck rotates the mandrel 106 about the vertical axis of thesecond leg 114. The laser 120 cuts the fabric second limb 128 at thedesired location.

To cut the body 124 of the fabric tube 122, the connection between thelaser 120 and the frame 118 is loosened so as to enable the laser toslide along the vertical frame 118 downwardly to locate the laser beamproximate to the location of the desired cut. The laser 120 is thensecured to the frame 118 at the desired height. When the chuck 102rotates, it causes the mandrel 106 to rotate about the vertical axis ofthe body 110. Once the laser 120 is powered on, it cuts the fabric tubebody 124 at the desired location.

Embodiments of the fabric cutting system 10 and method as describedherein can be utilized in medical applications, including, for example,in producing vascular and endovascular implants such as stents,stent-grafts, and heart valves. Some products made by the fabric cuttingsystem 10 and/or method may be applicable for use in various other typesof anatomical structures and locations, for example, in shunts betweenorgans and/or in gastrointestinal, pulmonary, neurological, and/or otherstructures and locations of a human or animal body.

The fabric cutting system 10 and/or method of the present inventionprovide(s) numerous advantages over conventional fabric cutting systemsand methods. For example, the present invention advantageously providesthe fabric cutting system 10 and method that provide reliably precisecuts. FIGS. 12 and 13 are microscopic views of the edges 66 of tubularfabrics 64 manually cut using a soldering iron according to aconventional cutting technique, and illustrate that the edge 66 of afabric 64 cut in this manner can be uneven and can include loose fibers.In contrast, FIGS. 14-16 are microscopic photographic views of the edges70 of the first leg 26, the second leg 28, and the body 24,respectively, of a tubular fabric 68 cut with a laser in accordance withan embodiment of the present invention. The fabric edges 70 shown inFIGS. 14-16 are evenly cut and are completely sealed. Accordingly, thefabric cutting system 10 and method of the present invention can providecut tubular fabrics 68 that meet quality control requirements for use inmedical applications.

Another advantage is that the present invention can provide the fabriccutting system 10 and method that provide a direct and unimpeded line ofcontact between the fabric cutting tool 48 and multiple legs 26, 28 onthe mandrel 16.

Another advantage is that the present invention can provide the fabriccutting system 10 and method in which positions of the mandrel 16 areinterchangeable so that the fabric cutting tool 48 can remain inalignment with a preset location relative to the longitudinal axis 38.

Another advantage is that the present invention can provide the cuttingmandrel 16 that can also be used as a heat-setting mandrel. Using themandrel 16 for both cutting and heat-setting avoids having to remove thefabric from one mandrel 16 and place it on another mandrel, therebyavoiding the risk of the fabric wrinkling and the possible difficulty ofplacing the fabric in the proper position on a heat-setting mandrel.

Another advantage is that the fabric on the legs 26, 28 of the mandrel16 can be cut first, before cutting fabric on the mandrel body 24, whichallows the fabric on the mandrel body 24 to better grip the mandrel body24 to help keep the fabric in place while the fabric on the legs 26, 28is being cut, resulting in more accurate first and second leg cuts.

Another advantage is that the present invention can provide the fabriccutting system 10 and method comprising a laser utilizing between about10 and about 35 watts to cut a fabric, thereby providing a straighteredge and a better seal of the fabric edge 70 than fabrics cut withlasers utilizing higher wattage.

Another advantage is that the present invention can provide the fabriccutting system 10 and method that are efficient and cost-effective. Forexample, embodiments of the fabric cutting systems 10 and methodsaccording to the present invention can reduce waste of fabric from about40-50 percent in conventional systems and methods to about 10 percent orless.

It should be understood that while the single chuck arrangement wasshown in a vertical orientation and the double chuck assembly was shownin a horizontal orientation, both assemblies may be oriented in eitherthe vertical or horizontal direction.

Although the present invention has been described with reference toparticular embodiments, it should be recognized that these embodimentsare merely illustrative of the principles of the present invention.Those of ordinary skill in the art will appreciate that the fabriccutting system and/or method of the present invention may be constructedand implemented in other ways and embodiments. Accordingly, thedescription herein should not be read as limiting the present invention,as other embodiments also fall within the scope of the presentinvention.

What is claimed is:
 1. A method of cutting a fabric, comprising:mounting a tubular fabric having a plurality of fabric limbs onto amandrel comprising a body, a first leg, and a second leg shorter thanthe first leg, the first leg comprising a leg extension removablyattached to a leg base; inserting the first leg into a center of achuck; rotating the mandrel within the chuck; cutting the entirecircumference of the fabric about the first leg at a location beyond theend of the second leg to provide a first fabric leg; removing themandrel from the chuck; removing the leg extension from the leg base;folding a portion of the first fabric leg extending beyond the leg baseback onto itself on the leg base; inserting the second leg into thechuck; rotating the mandrel within the chuck; and cutting the entirecircumference of the fabric about the second leg at a location beyondthe end of the leg base of the first leg.
 2. The method of claim 1,further comprising: removing the mandrel from the chuck; inserting themandrel body into the chuck; rotating the mandrel within the chuck; andcutting the entire circumference of the fabric about the mandrel body.3. The method of claim 2, wherein the fabric about the first leg and thesecond leg is cut before cutting the fabric about the mandrel body. 4.The method of claim 1, wherein the chuck is fixedly attached to a worksurface and configured to receive either one of the mandrel legs or bodyto rotatingly support the mandrel in the center of the chuck.
 5. Themethod of claim 1, further comprising heat-setting the fabric on themandrel.
 6. The method of claim 1, wherein cutting the fabric furthercomprises cutting the fabric with a cutting laser.
 7. The method ofclaim 6, further comprising programming the cutting laser with differentfocal distances for cutting different diameters on the mandrel.
 8. Themethod of claim 6, wherein cutting the fabric further comprises cuttingthe fabric with a multi-axis laser having a plurality of power heads,each power head adapted to emit a laser beam to a different focalcutting point.
 9. The method of claim 6, further comprising emitting alaser beam having between about 10 and about 35 watts of power to cutthe fabric.
 10. The method of claim 6, wherein the cutting laser ismounted on a frame and movable in a direction parallel to thelongitudinal axis of the mandrel.
 11. The method of claim 10, whereinthe cutting laser is moveable on a vertical axis.
 12. The method ofclaim 1, wherein the cut fabric comprises a vascular graft.